The Douve or Ouve is a river, 79 kilometres in length, which rises in the commune of Tollevast, near Cherbourg in the department of Manche. Ouve is considered its old name (Unva in ancient texts): Ouve appears to have been misspelled over the course of time as "Douve river" and then as "River of the Douve" (Douve literally means Ditch). The French name for this watercourse is la Douve.

The Douve is a navigable river owing to its flat bottom and adequate depth of flow. During the allied invasion of Hitler's Fortress Europa on D-Day, the river was the boundary between the allied left flank landing forces on Utah Beach (on its left bank and so to the west nearest Roune) and the bloody defensive battle that occurred at Omaha Beach. The Utah beach landings were part of contingency planning only scheduled after ample landing craft became available and designed to give the allies a leg up on taking a port city, in this case, Cherbourg for without such, any sustained offensive was foredoomed to failure from lack of logistical capacity. Had the landing craft been lacking, the river would have protected the exposed right flank of the allied invasion lodgement. With Utah in the plan, it was used to originate an offensive aimed squarely at the early domination of the peninsula and capture of Cherbourg as the British-Canadian forces were to attempt an early capture of the port of Caen (and eventually Rouen) at the opposite end of the lodgement. Both cities were well protected by their German defenders.